In a flexible-fuel vehicle, an internal combustion engine may be operated with more than one fuel type. For example, such an internal combustion engine may be powered by a mixture of gasoline and ethanol. Other mixtures are possible in which two types of liquid fuels are used, or a mixture of a liquid and a gaseous fuel is used, such as a mixture of gasoline and compressed natural gas (CNG). Injection timings determined for mixtures of liquid and gaseous fuels must account for differences in these fuels (e.g., density).
In some approaches, injection timings are calculated by an engine control unit in terms of a crank angle. More specifically, a crank angle corresponding to a start of fuel injection may be determined based on the revolution rate of the engine in which fuel injection is taking place in addition to its load.
The inventors herein have recognized an issue with such approaches. In particular, routines which calculate fuel injection timings based on engine revolution rate and engine load may be insufficient for injection of gaseous fuels or fuel mixtures including liquid and gaseous fuels, as such fuels may require a longer duration of injection. Other parameters which affect injection timing (e.g., physical dimensions of an ignition device, intake manifold, etc.) are further not accounted for.
Systems and methods for determining a start of fuel injection including a gaseous fuel in an internal combustion engine are provided.
In one example, an end of gas injection, a duration of gas injection, and a start of gas injection in an induction pipe of a cylinder of an internal combustion engine is determined based on one or more operating parameters. An earliest possible start of gas injection is further determined, and if the start of gas injection is before the earliest possible start of gas injection, at least one of the one or more operating parameters is modified such that the start of gas injection does not occur before the earliest possible start of gas injection.
In this way, fuel injection appropriate to fuel including at least one gaseous fuel is facilitated.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.